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Results for “Germ-Free Life”

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PubMed1976

The effect of a single dose of cyclophosphamide on the jejunum of specified pathogenfree and germfree rats.

After a single dose of cyclophosphamide (100 mg/kg) cell proliferation in the jejunum of the rat decreased within the first 24 h and returned to the initial level after 48 h. Under the influence of cyclophosphamide, an increased cell loss in germfree rats could be observed. Villus height and villus cell count tended to decrease. Changes in disaccharidase activity in mucosal scrapings with respect to protein and DNA content could not be demonstrated. An influence of presence or absence of bacterial flora could be observed.

Animals↗
PubMed1978

Effect of starvation on small intestinal enzyme activity in germ-free rats.

Starvation overnight and starvation for 48 h reduced the weight and the protein content of mucosal scrapings, but only minimally reduced the DNA content of the mucosal scrapings. The activity of sucrase and maltase was reduced by both periods of starvation. The activity of lactase and of acid and alkaline phosphatase, however, was less subject to starvation. There were striking differences in the response to starvation between the proximal, mid and distal third of the small intestine. The importance of the proper reference system was discussed.

Acid Phosphatase↗
PubMed1979

Rearing of conventional and gnotobiotic nonhuman primates (Pan troglodytes, Papio cynocephalus, Saguinus nigricollis).

Rearing techniques for conventional and gnotobiotic nonhuman primates are described. Up to four months of age there was no significant difference in weight gain between conventionally and gnotobiotically reared chimpanzees or baboons. After four months, gnotobiotic chimpanzees exceeded their conventional counterparts in weight gain, whereas conventional baboons showed higher weight gain than gnotobiotic baboons. Gnotobiotic chimpanzees and baboons had significantly lower absolute numbers of neutrophils than their conventional counterparts, but the absolute numbers of lymphocytes were not different. The gnotobiotic rearing of marmosets is also reported.

Animal Feed↗
PubMed1977

Feline Panleukopenia. I. Pathogenesis in germfree and specific pathogen-free cats.

Germfree and specific pathogen-free cats were inoculated panleukopenia vivus. Total leucocyte counts decreased significantly in both germfree and specific pathogen-free cats. Clinical illness was not seen in any germfree cat. Specific pathogen-free cats had anorexia and slight diarrhea 5-6 days after inoculation. None of the cats died. Both germfree and specific pathogen-free cats had thymic involution. No other gross lesions were seen. Tissues for histological virus isolation and immunofluorescence studies were taken daily from days 2 through 6 after inoculation. Virus-infected cells and lesions of panleukopenia were seen in the small intestine of both germfree and specific pathogen-free cats. The incidence of virus-infected cells and lesions was greater in specific pathogen-free cats than in germfree cats.

Animals↗
PubMed1977

Feline panleukopenia. II. The relationship of intestinal mucosal cell proliferation rates to viral infection and development of lesions.

Proliferation rates of small intestinal mucosal cells of noninfected germfree and specific pathogen-free kittens were compared to the incidence of infected cells and microscopic lesions in kittens experimentally infected with panleukopenia virus. Mucosal crypt length, cells per crypt, mitotic index and villous length were greater in specific pathogen-free kittens than in germfree kittens. Crypt cells per unit length and villous length per crypt length ratio were greater in germfree kittens. The cryptal cell proliferation rate of specific pathogen-free kittens was 2.24 times that of germfree kittens. Mucosal crypt length, cell per crypt and villous length were greater in the proximal jejunum than in the midjejunum of kittens within groups. Cell proliferation rates per crypt did not differ between areas of the intestine in kittens within groups. There were more virus-infected cells and lesions in specific pathogen-free kittens than in germfree kittens. The incidence of virus-infected cells and lesions was greater in the proximal jejumum and decreased along the small intestine.

Animals↗
PubMed2026

Microbiota-gut-muscle axis shapes fish muscle texture by regulating collagen synthesis.

BACKGROUND: Increasing studies have emphasized the communication network between the gut microbiome and host organs, revealing that such interactions significantly influence host physiological performances. However, whether a gut-muscle axis exists to regulate muscle quality in animal production is unknown. RESULTS: In two independent cohorts, the muscle hardness of tilapia subjected to a long-term faba bean diet exhibited significant inter-individual variation. RNA-Seq analyses of the high-hardness (H) and low-hardness (L) groups pointed to collagen-based extracellular matrix as a possible factor driving muscle hardness development. Transplantation of gut microbiota from the H donor resulted in enhanced collagen synthesis in gnotobiotic zebrafish. Muscular collagen deposition was featured with an increased abundance of gut Cetobacterium. Gnotobiotic models colonized with live C. somerae exhibited enhanced collagen synthesis. Integrated analyses of microbiome function, bacterial genome, and metabolic profiles identified acetate as a key effector of C. somerae. Acetate incubation upregulated collagen I expression in TGF-β-activated fibroblasts in an acetylation-dependent manner. Mechanistically, acetate promoted the acetylation of SMAD2/3, enhancing its nuclear transport and stability, which ultimately increased collagen expression. An acetate-supplemented feeding experiment corroborated these findings. CONCLUSION: The comprehensive results provided evidences that gut microbes regulated tilapia muscle texture through SMAD2/3 acetylation-driven collagen synthesis. This study expands our understanding of the multifaceted role of the gut-muscle axis in muscle physiology. Furthermore, our findings highlight that targeting gut microbiota and the downstream collagen synthesis pathway could be promising for manipulating muscle quality in animal production. Video Abstract.

Animals↗
PubMed2026

Capsaicin ameliorates glycemic levels via gut microbiota-derived 5-aminolevulinic acid in mice.

BACKGROUND: Capsaicin, a natural alkaloid in chili peppers, regulates glycemic levels; however, its mechanisms and therapeutic potential remain unclear. This study aimed to elucidate the role of gut microbiota and their metabolites in mediating capsaicin's glycemic regulatory effects. We conducted experiments in specific pathogen-free (SPF) and germ-free (GF) mice, transient receptor potential vanilloid 1 (TRPV1) receptor ablation studies, and fecal microbiota transplantation (FMT) to demonstrate the involvement of gut microbiota in capsaicin-mediated glycemic control. Metagenomics and metabolomics analyses were employed to identify key microbial strains and metabolic pathways. Keystone strains and metabolites were supplemented in GF mice without capsaicin intervention to validate their effects on glycemic regulation. In vitro co-culture experiments were performed to investigate the mutualistic relationships among keystone strains under capsaicin treatment. RESULTS: Gut microbiota constitute an important component of capsaicin-mediated glycemic regulation, acting in concert with but not solely dependent on TRPV1 signaling. Gut microbiota altered by capsaicin promote the production of 5-aminolevulinic acid (5-ALA), which contributes to heme synthesis and enhances glycemic control. Supplementation with Akkermansia muciniphila, Ligilactobacillus murinus, or 5-ALA in GF mice recapitulates the glycemic benefits of capsaicin. Furthermore, capsaicin enriches Akkermansia muciniphila, which in turn supports the growth of Ligilactobacillus murinus. CONCLUSION: Capsaicin-induced changes in the gut microbiota promote 5-ALA synthesis, leading to improved glycemic control. These findings suggest that dietary or probiotic interventions targeting gut microbiota, particularly Akkermansia muciniphila and 5-ALA, may offer promising strategies for managing glycemic disorders, including type 2 diabetes (T2D). Video Abstract.

Animals↗
PubMed1975

Diet, mucosal architecture and epithelial cell production in the small intestine of specified-pathogen-free and conventional rats.

Upper jejunum and terminal ileum were examined in specified-pathogen-free (SPF), conventional and conventional after SPF rearing (ex-SPF) rats. The effect of 2 differential diets on the last 2 groups was examined. Ex-SPF rats had taller villi and deeper crypts than SPF rats, but similar crypt to villus ratios and cell production rates. Ex-SPF rats had similar crypt depth and jejunal villus height to conventional rats on the same diet, but taller ileal villi and a lower cell production rate. Even after 6-8 weeks, in a conventional environment, ex-SPF rat intestine was still not identical with conventional rat intestine. Diet had a significant effect on mucosal architecture, and a smaller effect on cell production rate. It is concluded that diet, microbiological status of colony of origin, and environment after weaning, can all affect mucosal architecture and epithelial cell production, and should be properly controlled in experimental studies.

Animal Feed↗
PubMed1975

The microbiological and parasitological colonisation of specified-pathogen-free mice maintained in a conventional animal house.

2 groups of 44 specified-pathogen-free (SPF) mice, caged in groups of 4, were housed at weaning either in isolation in a building housing conventionally-reared animals, or in contact with those animals. 4 mice from each group were examined for microbiological flora and 4 for parasites at intervals for up to 90 days after transfer. Proscribed bacteria were isolated from the "in contact' group after 42 days and endoparasites were observed by 16 days and thereafter. No proscribed bacteria were isolated from the other group, although some endoparasites were observed by 16 days. Proscribed bacteria were shown to be present in the conventionally-reared animals at weaning and ecto- and endoparasites by day 16 and thereafter. It is suggested that it may be possible to maintain SPF animals outside a SPF Unit for short periods of time, and that with great care the animals remain free of proscribed microflora.

Animal Feed↗
PubMed1977

The use of biotyping of Enterobacteriaceae as an evaluation of the isolation efficacy of laboratory animals.

2 sets of data are given of biotyping the Enterobacteriaceae from the faecal flora of SPF rats and cats housed with different isolation arrangements. The method is presented as an evaluation of the isolation efficiency of laboratory animals. Biotypes which were determined on almost every occasion belonged to the resident flora of the animals while those found occasionally represented contamination. Contaminating bacteria are cleared from an SPF breeding unit by colonization resistance and the continuous efflux of animals from the unit. A parameter of isolation efficacy is the number of different biotypes determined in time. With optimal isolation arrangements a stable bacterial flora of permanently colonized biotypes is obtained in the animals.

Animals↗
PubMed1977

Congenital venous hypoplasia in the liver of rats.

Narrowed and rudimentary portal vein branches were observed in the livers of specified-pathogen-free rats which, at the age of 6-11 weeks, showed poor condition and reatrded growth. At autopsy abdominal venous distension and congestion suggestive of portal hypertension and collateral circulation appeared to have developed. The cause of the observations and their significance in view of the use of the rats are unknown.

Animals↗
PubMed1978

Selective decontamination of the digestive tract of Syrian hamsters.

Conventional Syrian hamsters colonized with aerobic gram-negative bacteria such as Pasteurella pneumotropica and various Enterobacteriaceae species were successfully and permanently freed from these microorganisms by oral treatment for 4 weeks with dihydrostreptomycin and 'Orabase' premixed with appropriate antibiotics. Concomitant oral treatment with dimetridazol for the elimination of intestinal flagellates was unsuccessful. During treatment the animals were maintained under germ-free isolation conditions.

Animals↗
PubMed1978

Attempted transmission of Entamoeba coli to specified-pathogen-free rodents.

An attempt was made to establish whether human Entamoeba coli was transmissible from man to laboratory rodents. Cysts from 15 samples of human and 4 of primate stool were passaged into specified-pathogen free guinea-pigs, rats and mice. In only 1 instance were cysts established in mice and, eventually, in rats.

Amebiasis↗
PubMed1979

Effect of vitamin B6 deficiency on the levels of several water-soluble vitamins in tissues of germ-free and conventional rats.

The influence of vitamin B6 deficiency on the levels of several water-soluble vitamins and on acetyl-coenzyme A carboxylase activity was investigated using of germ-free and conventional rats. Judging from the vitamin B6 levels in tissues and the percent of decrease, the degree of vitamin B6 deficiency was more severe in the tissues of deficient germ-free rats than in deficient conventional rats. Nicotine acid, pantothenic acid and biotin levels per wet weight significantly decreased in the liver of vitaminB6-deficient germ-free rats, and nicotine acid levels per wet weight significant decreased in the liver of deficient conventional rats. In the kidney of vitamin B6-deficient germ-free rats, a significant decrease in riboflavin and biotin levels was observed, although there was no observable difference in riboflavin, nicotinic acid, biotin and patothenic acid levels in the kidney of deficient conventional rats. From an enzymatic standpoint, acetyl-coenzyme A carboxylase activity was especially significantly decreased in both germ-free and conventional rats fed a vitamin B6-deficient diet, and the percent od decrease was more in germ-free rats than in conventional ones. These findings suggest that vitamin B6 deficiency had stronger effects on the levels of water-soluble vitamins in germ-free rats compared with conventional rats.

Acetyl-CoA Carboxylase↗